The Indian government has said Pakistan will be given evidence that its spy agency, ISI, was behind the July train blasts in Mumbai that killed 186.

Mumbai police arrested four people and on Saturday said the attacks were carried out by Pakistan-based Islamist militant group Lashkar-e-Toiba.

Pakistan quickly denied the accusation as "baseless" and demanded proof.

Analysts say the war of words may mean that the recent moves to revive the peace talks may suffer a setback.

More than 1,000 people were wounded in the blasts.

Deeds, not words

"We will take the issue up with Pakistan in view of new evidence," Indian Foreign Secretary Shiv Shankar Menon said without specifying.

"We will judge them [Pakistan] not by their immediate reaction of verbal statements, but by what they actually do about terrorism," Mr Menon said.

He said India wanted Pakistan to "not only talk, but act too".

India postponed peace talks with Pakistan after the bombings, but Indian Prime Minister Manmohan Singh and Pakistani President Pervez Musharraf met recently in Cuba and said they had agreed to resume the negotiations.

The two sides agreed to set up a joint mechanism to fight terror and the foreign secretaries of the two countries are due to meet in Delhi later in November to discuss the issue.